37 research outputs found
The selective role of nitrite in the PAO/GAO competition
Proliferation of Glycogen Accumulating Organisms (GAOs) accounts as one of the major bottlenecks in biological phosphorus removal systems. GAO outcompeting polyphosphate accumulating organisms (PAOs) results in lower P-removal. Thus, finding optimal conditions that favour PAO in front of GAO is a current focus of research. This work shows how nitrite can provide a novel strategy for PAO enrichment. A propionate-fed GAO- nriched biomass (70% Defluviicoccus I, 18% Defluviicoccus II and 10% PAO) was subjected more than 50 d under anaerobic-anoxic conditions with nitrite as electron acceptor. These operational conditions led to a PAO-enriched sludge (85%) where GAO were washed out of the system (<10%), demonstrating the validity of the new approach for PAO enrichment. In addition, the presented suppression of Defluviicocus GAO with nitrite represents an add-on benefit to the nitrite-based systems since the proliferation of non-desirable GAO can be easily ruled out and added to the other benefits (i.e. lower aeration and COD requirements)
Methanol-driven enhanced biological phosphorus removal with a syntrophic consortium
The presence of suitable carbon sources for enhanced biological phosphorus removal (EBPR) plays a key role in phosphorus removal from wastewater in urban WWTP. For wastewaters with low volatile fatty acids (VFAs) content, an external carbon addition is necessary. As methanol is the most commonly external carbon source used for denitrification it could be a priori a promising alternative, but previous attempts to use it for EBPR have failed. This study is the first successful report of methanol utilization as external carbon source for EBPR. Since a direct replacement strategy (i.e., supply of methanol as a sole carbon source to a propionic-fed PAO-enriched sludge) failed, a novel process was designed and implemented successfully: development of a consortium with anaerobic biomass and polyphosphate accumulating organisms (PAOs). Methanol-degrading acetogens were (i) selected against other anaerobic methanol degraders from an anaerobic sludge; (ii) subjected to conventional EBPR conditions (anaerobic + aerobic); and (iii) bioaugmented with PAOs. EBPR with methanol as a sole carbon source was sustained in a mid-term basis with this procedure
Planta de producciĂłn de anilina
El objetivo de este proyecto es el diseño de una planta para la producciĂłn de anilina a partir de nitrobenceno. Este proyecto ha de ser viable en tĂ©rminos de diseño y economĂa, además de cumplir con la normativa y legislaciĂłn vigentes
Facing current EBPR bottlenecks in view of full-scale implementation
Des de fa temps s’han estudiat els processos d’eliminaciĂł biològica de fòsfor (EBPR) en aigĂĽes residuals, però la seva implementaciĂł a escala real ve associada moltes vegades a fallades no esperades. S’han detectat interaccions negatives amb el procĂ©s d’eliminaciĂł de nitrogen i matèria orgĂ nica que no s’havien previst en l’estudi dels mateixos de manera individual. Aquesta tesi aprofundeix en la caracteritzaciĂł, l’estudi i la soluciĂł de problemes existents a l’hora d’implementar l’eliminaciĂł biològica de fòsfor en aigĂĽes residuals conjuntament amb l’eliminaciĂł biològica de matèria orgĂ nica i nitrogen. La investigaciĂł duta a terme en aquesta tesi tĂ© dos enfocaments diferents dins d’aquest marc. D’una banda s’estudien les causes de la interacciĂł negativa entre els processos d’eliminaciĂł biològica de nitrogen i de fòsfor. D’altra banda s’estudia la possibilitat d’utilitzar, per part dels organismes acumuladors de fòsfor (PAO), fonts de carboni alternatives, que tambĂ© s’utilitzen en el procĂ©s d’eliminaciĂł de nitrogen. En el primer lloc, s’estudia una nova estratègia per l’eliminaciĂł de nutrients (nitrogen i fòsfor) que consisteix en la bioaugmentaciĂł de microorganismes PAO dins d’un sistema de nitrificaciĂł i desnitrificaciĂł. En aquest estudi es va comprovar que una configuraciĂł de SBR amb una fase anòxica amb dues alimentacions i una fase aeròbica permet aconseguir nitrificaciĂł, desnitrificaciĂł i EBPR. Un punt clau per l’èxit d’aquesta estratègia Ă©s proporcionar condicions operacionals adequades per evitar els problemes de “rising”. Es proporcionar una fase aeròbia amb la suficient durada per assegurar el consum del PHA acumulat pels PAO, i evitar la disponibilitat de font de carboni requerida per la desnitrificaciĂł. En aquest mateix context tambĂ© s’estudia la interacciĂł de diferents espècies intermèdies del procĂ©s d’eliminaciĂł de nitrogen, com sĂłn el nitrit i el nitrat, en el procĂ©s EBPR. D’altra banda, s’ha estudiat un dels principals problemes per a implementar a nivell real l’EBPR, la manca d’à cids grassos volĂ tils a l’aigua residual d’entrada al procĂ©s. És per això que, en segon lloc, s’han estudiat diverses estratègies per a la utilitzaciĂł de fonts de carboni diferents a les convencionals en el procĂ©s EBPR. S’han provat fonts de carboni que actualment s’utilitzen en el procĂ©s d’eliminaciĂł de nitrogen, com sĂłn el metanol i el glicerol, i que, per tant, abaratirien els costos quan ens trobem aigĂĽes residuals amb poca DQO disponible per dur a terme l’eliminaciĂł simultĂ nia de nitrogen i fòsfor. Les estratègies que es proven tambĂ© sĂłn dues: la primera Ă©s la substituciĂł directa de la font de carboni convencional (Ă cid propiònic) per la font de carboni en qĂĽestiĂł dins d’un sistema enriquit en microorganismes PAO. La segona estratègia, mĂ©s innovadora, Ă©s la formaciĂł d’un consorci microbiĂ amb llots de digestiĂł anaeròbia, prèviament seleccionat, amb microorganismes PAO on els primers seran capaços de fermentar la font de carboni mĂ©s complexa cap a Ă cids grassos volĂ tils de cadena curta (Ă cid acètic i propiònic) que seran utilitzats pels PAO per dur a terme el procĂ©s EBPR. En el darrer capĂtol de la tesi, s’estudia una nova estratègia per a aconseguir uns llots enriquits majoritĂ riament amb microorganismes PAO. Aquest procediment permet eliminar del sistema aquells microorganismes competidors (GAO) que capten la font de carboni que hi ha disponible pels PAO i perjudiquen al procĂ©s EBPR. L’aplicaciĂł d’aquesta estratègia va resultar en un llot amb un 85% de PAO i en el rentat dels GAO del sistema.Enhanced biological phosphorus removal (EBPR) has been extensively studied, but its implementation at full-scale is still associated to unpredictable failures. Furthermore, when EBPR is implemented simultaneously to nitrogen and organic matter removal, some negative interactions have been found, while individually does not occur.
This thesis aims to improve the understanding of EBPR and solve some of the issues reported when EBPR is implemented in wastewater treatments together with biological removal of nitrogen and organic matter.
The research conducted in this thesis has two different approaches within this framework. On the one hand, the negative interaction between the nitrogen and phosphorus removal processes has been studied. On the other hand, the possibility to use alternative carbon sources, also used in nitrogen removal, has been assessed by developing novel strategies focused on obtaining new syntrophic consortia for application in EBPR.
In chapter 4, new insights for simultaneous nitrogen and phosphorus removal are presented. These strategies are based on the bioaugmentation of PAO microorganisms in nitrification/denitrification systems. A cycle configuration with an anoxic phase with two feedings and an aerobic phase was used to achieve nitrification, denitrification and EBPR. A key point for the success of this strategy was to provide proper operational conditions to avoid rising problems. Enough aerobic phase length was required to ensure complete PHA depletion for PAO microorganisms, which avoided the carbon source availability required for denitrification.
In this context, the interaction of different intermediates of the nitrogen removal process, such as nitrite and nitrate, on the EBPR processes was studied. The conclusion of such experiments was that intermediate products of the nitrogen removal process, such as nitrate, can affect EBPR process when PAO microorganisms have not been previously acclimated to these conditions.
Low concentration of volatile fatty acid in wastewaters has been also reported to be one of the main hurdles problems to implement EBPR process in full-scale WWTPs. For this reason, Chapter 5 presents the studies done in order to use different carbon sources for EBPR. Two carbon sources commonly used in nitrogen removal processes, namely methanol and glycerol, were tested, resulting in a cost reduction when nitrogen and phosphorus were removed simultaneously in wastewaters with low COD content. Two different strategies were assessed: first, the direct replacement of conventional carbon source (propionic acid) to the desired carbon source in a PAO-enriched sludge system. The second strategy, a novel one, was to develop a consortium of anaerobic sludge, comprising previously selected microorganisms, and PAO where the first ferment the complex carbon source to short-chain volatile fatty acids (i.e. acetic and propionic acid) which are subsequently used by the PAO in the EBPR process.
Finally, Chapter 6 presents the study of a new strategy to achieve a predominantly PAO-enriched sludge, removing GAO, which uptake significant proportions of the carbon source available for EBPR. The application of this strategy resulted in the 85% of PAO in the enriched sludge, washing out GAO of the system
Estudio electroforético de enfermedades que cursan con disproteinemia
[spa] Gracias a los trabajos realizados con motivo de la presente tesis, se ha hallado un mĂ©todo de inmunoelectroforesis que facilita su obtenciĂłn, pudiĂ©ndola convertir en mĂ©todo rutinario en hospitales, clĂnicas y laboratorios de análisis. Este sistema facilita muchĂsimo su obtenciĂłn, disminuyendo las dificultades que hasta ahora habĂa en las electroforesis y en las inmunoelectroforesis, pues el motivo de que no se fueran practicando extensivamente hasta ahora era la dificultad del mĂ©todo, en el que utilizaban aparatos para preparar el gel y en la introducciĂłn del suero problema e inmunosuero, utilizando el sistema más asequible, que es el de Scheideger, el cual utiliza una capa de agar encima de un porta. En cambio, en el sistema que presentamos se utilizan unas tiras ya preparadas de acetato de celulosa, que se encuentran actualmente en España, en las que ya va colocada la capa de agar-gel; de este modo se encuentran gelatinizadas y se conservan casi indefinidamente en un baño al 50% de metanol. Estas tiras son las que se utilizan para electroforesis en acetato de celulosa gelatinizada
Estudio electroforético de enfermedades que cursan con disproteinemia
[spa] Gracias a los trabajos realizados con motivo de la presente tesis, se ha hallado un mĂ©todo de inmunoelectroforesis que facilita su obtenciĂłn, pudiĂ©ndola convertir en mĂ©todo rutinario en hospitales, clĂnicas y laboratorios de análisis. Este sistema facilita muchĂsimo su obtenciĂłn, disminuyendo las dificultades que hasta ahora habĂa en las electroforesis y en las inmunoelectroforesis, pues el motivo de que no se fueran practicando extensivamente hasta ahora era la dificultad del mĂ©todo, en el que utilizaban aparatos para preparar el gel y en la introducciĂłn del suero problema e inmunosuero, utilizando el sistema más asequible, que es el de Scheideger, el cual utiliza una capa de agar encima de un porta. En cambio, en el sistema que presentamos se utilizan unas tiras ya preparadas de acetato de celulosa, que se encuentran actualmente en España, en las que ya va colocada la capa de agar-gel; de este modo se encuentran gelatinizadas y se conservan casi indefinidamente en un baño al 50% de metanol. Estas tiras son las que se utilizan para electroforesis en acetato de celulosa gelatinizada